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TECHNICAL PAPER

incorporated into concrete as cement replacement. As with SL disturbance by the EDI, which combines the environmental
and FA, upstream energy, raw materials, and emissions are not impacts with the functional unit to provide a measure of both
included in this process, which is a common and conservative environmental and technical performance. The results for the
assumption [18, 19] . SF transportation is modeled based on SF mix designs containing the alternative concrete constituents
sources and modes of transportation that are typical for the are calculated relative to the results for the 100GU mix
Ontario region. The corresponding emissions factors are shown design, which are normalized to one. This allows for a quick
in Athena and the worst-case transportation scenario is from determination of whether the mix designs containing alternative
[4]
Niagara Falls (New York, USA) via St Basile (Quebec, Canada) to concrete constituents offer an improvement over conventional
Toronto (Ontario, Canada) (1623 km). concrete (EDI<1) or whether these mix designs have a higher
environmental disturbance than conventional concrete for a
3.2.4 Limestone Process given functional performance (EDI >1).

For limestone cement production, the transportation process of In Equation 2, the index ‘i’ refers to the four impact categories
raw materials is not included. This is because cement production included in this study (namely acidification, global warming
facilities are typically located at limestone quarries, and so there potential, resource depletion, water depletion). The index
is no transportation requirement for these materials [20] . As a ‘j’ refers to each of the six mix designs included in this study
result, the only added process for limestone cement production as described in Table 1. These indices are used to calculate
[4]
is for the physical grinding of raw materials .
EDIs that incorporate LCA and LCIA results from four impact
categories. Note, base material mix is 100GU.
3.2.5 Admixture Production Process
Data for air entraining admixtures has been gathered from an Equation 2
environmental product declaration prepared by the European 4 LCIA result impact category i, alt. material j 1
Federation of Concrete Admixtures Associations [21] . The EDI j =∑ x weighting x
LCIA result impact category i, base material FU

environmental product declaration includes the raw materials, i=1
emissions to air, emissions to soil, and emissions to water. where i = 1 to 4 and corresponds to impact category,
j = 1 to 5 and corresponds to alternative materials,
4. LCA – LIFe CyCLe IMPACt AssessMeNt FU is functional unit,
and weighting is the LCIA fraction taken for each impact category
(LCIA) MetHODOLOGy
In order to compile the LCI data and conduct the impact As shown in Equation 2, the LCIA results for each impact
assessment, GaBi 6 software package was used [22] . GaBi 6 is category were divided by the corresponding results for 100GU,
packaged with several impact assessment methods, including the base case mix design. The LCIA fraction of an impact
the International Reference Life Cycle Data System method category is multiplied by the “weighting” scheme, summed
which was used for this study [23] . LCIA consists of five steps in and divided by the function unit (FU). An initial weighting of
according to the ISO 14040 standard [24] : (1) selection of impact (0.25:0.25:0.25:0.25) was applied to acidification, global warming,
categories, category indicators and characterization models; resource depletion, and water depletion respectively to combine
(2) assignment of LCI results to the selected impact categories; these categories. Four other alternative weightings (shown
(3) calculation of category indicator results; (4) calculating the in Table 3) were also applied to evaluate the sensitivity of the
magnitude of category indicator results relative to reference results, as discussed in Section 6.2.1. A higher EDI indicates a
information; and (5) converting indicator results of different concrete with a lower environmental performance (and a higher
impact categories by using numerical factors based on value- environmental disturbance).
choices. Four impact categories, i) acidification, ii) global
warming potential, iii) resource depletion and iv) water table 3: weighting schemes
depletion, were selected for the analysis and the extent of WEIGhTING ACIDIFICA- GlOBAl RESOuRCE WATER
international consensus on their classification and SChEME TION WARMING DEplETION DEplETION
characterization, as described in Stranddorf and Anders pOTENTIAl
Schmidt [25] . In LCA, characterization factors are science-based
factors that are used to convert LCI data to actual environmental 1 0.25 0.25 0.25 0.25
impacts [26] . 2 0.7 0.1 0.1 0.1
3 0.1 0.7 0.1 0.1
5. LCA – INteRPRetAtION
4 0.1 0.1 0.7 0.1
This section describes the methodology used to interpret
the LCA results by calculating the extent of environment 5 0.1 0.1 0.1 0.7

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